THE  SOLUBILITY  OF  NORMAL  BUTYL  ALCOHOL  IN  AQUEOUS 
SOLUTIONS  OF  INORGANIC  SALTS 


BY 

NELSON  JOSEPH  ANDERSON 

B.  S.,  Kansas  State  Agricultural  College,  1920 


THESIS 

SUBMITTED  IN  PARTIAL  FULFILLMENT  OF  THE  REQUIREMENTS 
FOR  THE  DEGREE  OF  MASTER  OF  SCIENCE  IN  CHEMISTRY 
IN  THE  GRADUATE  SCHOOL  OF  THE 
UNIVERSITY  OF  ILLINOIS 

1922 


URBANA,  ILLINOIS 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/solubilityofnormOOande 


< 


UNIVERSITY  OF  ILLINOIS 


0. 

to 

r i 


THE  GRADUATE  SCHOOL 


-192-2 


1 HEREBY  RECOMMEND  THAI'  THE  THESIS  PREPARED  UNDER  MY 
SUPERVISION  BY Nelson  J*  Anderson — 

ENTITLED THE  SOLUBILITY  OE  NORMAL  BUTYL  ALCOHOL  XL 

AQUEOUS  SOLUTIONS  OE  INORGANIC-SALTS 

BE  ACCEPTED  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR 
THE  DEGREE  OF Master- of  - Science 


Head  of  Department 


In  Charge  of  Thesis 


Recommendation  concurred  in* 


Committee 


on 


Final  Examination* 


Required  for  doctor’s  degree  but  not  for  master’s 


table  of  contents 


Page 


1 

INTRODOCTIOh. 

1-2 

11 

EXPERIMENTAL  PART 

( a)Di scussion  of  Methods 

3-6 

Cb)Tests  of  Methods  Chosen 

7-8 

III 

DATA  AND  GRAPHS 

8-19 

IV 

DISCUSSION  OF  DATA  ALD  RESULTS 

( a) Cations 

20-21 

(h)  Anions 

2122 

(c)  Colloids 

22 

(d)  H-ion  Concentration 

23 

V 

SUMMARY 

24 

VI 

BIBLIOGRAPHY 

25 

ACKNO  V/LED  GEME1TT 


The  author  wishes  to  express  his  sincere 
thanks  to  Dr .E.K. Carver  and  Dr . J.H* Reedy  for 
their  constant  advice  and  kind  supervision  of 


this  work 


„ . , . , , 

. 


J 


THE  SOLUBILITY  OE  NORMAL  BUTYL  ALCOHOL 
IN  AQUEOUS  SOLUTIONS  OE 
INORGANIC  SALTS 
I 

INTRODUCTION 

The  purpose  of  this  research  is  to  determine  the  solubility  of 
a non-polar  organic  compound  in  qqueous  solutions  of  various  concent- 
rations of  inorganic  salts.  This  data, it  is  hoped, will  be  useful  to 
make  comparisons  with  facts  khown  about  precipitation  of  colloids  by 
means  of  electrolytes , and  to  make  some  general  conclusions, Thi s work 
can  be  rightfully  looked  upon  as  a problem  in  colloidal  chemistry 
because  one  can  select  an  organic  substance  ,as  gelatin, which  will 
fonn  a hydrosol  when  it  is  dissolved  in  water  or  in  certain  aqueous 
solutions  of  electrolytes.  Thus, when  one  determines  the  amount  of 
such  a substance  that  will  dissolve  in  a given  solution  of  an  electro- 
lyte,he  is  measuring  the  precipitating  power  of  the  electrolyte. 

Since  the  time  of  Thomas  Graham, a considerable  of  work  has 
been  done  by  colloid  chemists  upon  the  precipitation  of  colloids  by 
various  electrolytes , and  plenty  of  data  is  available.  Asearch  thru 
the  literature  shows , however, that  no  data  on  the  theme  of  this  thesis 
is  available. 

Inasrnuchas  it  is  possible  to  prepare  a solution  of  a sol 
which  is  transparent , it i s suggested  that  transparent  solutions  of  an 
organic  compound  in  water  or  in  an  aqueous  solution  may  behave  like 
an  emulsoid  or  a suspensoid.  To  illustrate  this  point, if  one  will 
shake  together  a solution  of  NaCl  and  the  proper  amount  of  n-butyl 
alcohol, he  will  notice  an  opalescence  in  the  mixture ,whi ch  upon  stand- 
ing for  30  min.  will  disappear.  If  the  mixture  is  shaken  well  again, 


, 

- 

■ 

, 

« 


< 


, 


I 


. 


2 


the  opalescence  will  reappear.  Thus, one  is  justified  in  "believing 
that  the  mixturS  contains  an  emulsoid.  For  this  reason, and  for  the 
reason  that  it  is  easy  to  find  an  organic  compound  which  is  not  an 
electrolyte, it  was  decided  to  use  an  organic  compound  for  the  tests 
made  in  this  work. 


EXPERIMENTAL 

Some  method  for  the  quantitative  determination  of  the  amount 
of  a chosen  organic  solute  that  would  dissolve  in  a given  aqueous 
solution  of  an  inorganic  salt  was  deemed  feasible  for  getting  data 
desired.  A few  methods  of  solubility  determination  were  tried  with- 
out success.  They  follow  in  the  order  in  which  they  were  tried. 

Whatever  method  is  used  must  insure  equilibrium  in  every  sol- 
ubility tewt  made.  Hence, we  chose  at  the  start  a device  for  agitating 
the  liquid  under  investigating.  A 100c.  c.  wide  muoth  bottle  was  fittec. 
with  a rubber  stopper  thru  which  a glass  stirer  could  be  operated  by 
a small  electric  motor.  The  stopper  contained  a short  delivery  tube 
thru  which  the  organic  eolufete  could  be  admitted  from  a burette  into 
the  liquid  inside  the  bottle.  Ethyl  ether  was  chosen  as  the  organic 
solute  to  use  in  this  experiment.  A little  ether  was  introduced  upon 
some  water  contained  in  the  bottle  and  the  stirrer  was  set  in  motion. 
After  a little  stirring, the  motor  was  stopped, and  it  was  observed 
whether  all  of  the  ether  added  had  dissolved.  If  not, a little  more 
was  added  from  the  burette, and  so  on, until  it  was  hoped  only  a single 
drop  of  ether  would  remain  in  excess. 

The  chief  advantage  of  this  method  is  that  the  error  thru  losn 
of  vapor  is  reduced  to  a minimum.  Its  disadvantage  is  that  one  cannot 
determine  accurately  when  the  "end  pbint"  is  reached.  Altho  any  excesn 
of  ether  added  would  float  on  the  surface  of  the  water, one  could  not 
determine  how  much  ether  to  add  to  get  even  a fairly  accurate  solubil- 
ity determination. 

An  attempt  to  improve  the  accuracy  that  could  be  gotten  with 
this  apparatus  consisted  in  the  addition  of  a small  amount  of  an  ind- 
4 ^■=■^■,-^^--■10-.-  _ 


.. 

- 


. . 


, 


, 

< 


« 

. 


* 


, 


- /• 


4 


icator  to  the  ether.  Para-nitroso  dimethyl  aniline  is  green  and  is 
very  soluble  in  ethyl  ether.but  only  very  slightly  soluble  in  water. 
It  pnpTed  unsatisfactory. 

This  experiment  suggested  that  a container  siich  as  volumetric 
flask  would  be  an  improvement.  Then,  one  would  be  able  to  determine 
more  easily  when  a single  drop  of  excess  ether  is  added. Such  a flask 
would  limit  the  upper  exposed  surface  of  the  liquid  inside  it  to  the 
area  of  the  cross  section  of  the  neck  of  the  flask. 

A piece  of  rubber  tubing  about  5 in. long  wqs  used  to  connect 
the  jet  of  a glass  burette  to  a short  jet  made  from  a piece  of  glass 
tubing.  This  latter  jet  wa®  made  quite  small  so  that  a liquid  flowing 
thru  it  from  the  burette  would  flow  very  slowly.  This  jet  was  lowered 
in  some  water  in  a 200c. c.  volumetric  flask  until  it  reached  the 
bottom  of  the  flask.  It  was  hoped  that  the  ether  would  flow  out  of  th< 
jet  so  slowly  that  it  would  dissolve  in  the  water  before  any  droplets 
reached  the  surface  of  the  water.  There  would  be  two  advantages  in 
this  kind  of  a scheme.  Loss  of  ether  due  to  evaporation  would  be 
small.  As  soon  as  droplets  began  to  reach  the  surface  of  the  liquid 
in  the  flask, the  "end  point"  would  be  attained.  A litt-ifc  agitation  of 
the  liquid  by  gentle  shaking  of  the  flask  was  thought  to  be  sufficien' 
This  method  did  not  succeed  because  the  rate  of  miscibility  of  ether 
with  water  or  with  aqueous  solutions  of  salts  is  very  slow.  Also, the 
droplets  of  ether  instantaneously  shot  to  the  surface  when  first  ad- 
mitted to  the  water.  The  large  difference  in  their  densities  and  the 
low  adhesive  force  between  the  liquids  partly  account  for  the  failure 
of  this  method. 

One  method  which  would  undoubtedly  work  wellf\be cause  it 


requires  slow  work  for  manipulation.  A small  excess  of  an  organic 


< 


solute  could  "be  shaken  with  an  aqueous  solution  in  a separatory  fun-& 
nel  that  has  a stem  with  a very  small  bore.  After  the  mixture  is  shak- 
en until  equilibrium  is  reached, the  excess  of  organic  solute, being  of 
greater  density , would  appear  at  the  upper  surface  of  the  mixture  and 
an  accurate  separation  could  be  made.  In  this  way, the  determinations 
could  be  either  gravimetric  or  volumetric.  A small  but  negligible  er- 
ror would  be  introduced  by  the  amount  of  aqueous  solution  or  the  elec, 
trolyte  which  is  dissolved  in  the  excess  of  the  organic  solute. 

One  difficulty  to  overcome, as  revealed  by  the  foregoing  att- 
empt s,was  to  find  an  organic  solute  which  has  physical  constants  app- 
roximately equal  to  the  physical  constants  of  water.  Such  a compound 
would  not  introduce  appreciable  error  thru  evaporation.  Ether  was  ob- 
jectionable because  of  its  low  boiling  point  and  its  volatility.  Fur- 
thermore, a compound  which  has  a high  adhesiire  force  with  water  and 
with  aqueous  was  needed; so  that, when  solubility  determinations  are  be- 
ing made , equilibrium  can  be  readily  attained.  A compound  that  is 
very  soluble  is  undesirable. 

Iso-butyl  alcohol  was  selected  at  first  as  it  fulfils  these  re 
quirements ,but  wras  later  rejected  because  of  the  difficulty  of  purify- 
ing it.  The  solubility  results  obtained  with  iso-butyl  alcohol  vrould 
not  check.  The  description  of  a very  elaborate  method  for  the  purific- 
ation of  higher  alcohols  is  given  in  an  article  in  the  J. A. C. S. , March 
1921. pp. 561.  The  authors  suggested  that  normal  butyl  alcohol  can  be 
very  satisfactorily  purified  by  ordinary  fractional  distillation. 

Normal  butyl  alcohol  was  selected  for  the  solute  used  in  the 
solubility  determinations  made  in  this  work.  The  boiling  point  of  nor- 
mal butyl  alcohol, as  given  in  the  article  mentioned  above, is  117.7  ae- 
grees  C.  at  760  mm. pressure.  The  fraction  used  for  the  determinations 
in  this  work  was  that  which  diatilled  over  above  116  degrees  C. 


6 

Solubility  tests  with  this  grade  of  alcohol  made  in  pure  water  and  in 
several  salt  solutions  gave  good  checks , dhowing  the  alcohol  to  be  of 
sufficient  purity.  16.85  c.c.  of  this  grade  of  n-butyl  alcohol  will 
dissolve  in  180  c.c.  of  distilled  water  at  25  degrees  C. 

The  method  of  solubility  determination  used  is  as  follows; 
180-190  c.c.  of  an  aqueous  solution  under  investigation  was  put  in  a 
200  c. c. volumetri c flask  and  n-butyl  alcohol  was  admitted  from  a bur- 
ette so  that  the  amount  added  could  be  read  off.  The  "end  point"  was 
reached  when  a single  drop  of  alcohol  in  excess  floated  on  top  of  the 
mixture  in  the  flask  after  equilibrium  is  reached.  It  was  always  mana 
ged  so  that  the  total  volume  of  mixture  in  the  flask  would  be  great 
enough  to  raise  the  upper  surface  into  the  neck  of  the  flask.  This 
made  it  possible  to  determine  whenp,drop  of  excess  alcohol  appeared. 

In  most  cases  tried, a few  droplets  would  appear  at  the  surface  after 
a vigorous  shaking  as  soon  as  the  amount  of  alcohol  added  was  within 
onehalf  of  a c.c.  of  the  amount  required  for  saturation.  Further  shak- 
ing would  usually  cause  all  of  these  droplets  to  disappear.  It  was  un 
necessary , however , to  reach  the" end  point"by  the  slow  process  of  shak- 
ing the  mixture  after  each  small  addition  of  alcohol  until  all  drop- 
lets had  disappeared.  Every  solubility  test  was  made  in  duplicate  in 
two  separate  volumetric  flasks.  The  first  one  in  eqch  determination 
gave  the  approximate  equilibrium  value; the  second  served  to  get  a 
more  accurate  value  and  to  check  the  first.  A glass  stirrer  was  used 
sometimes  to  hasten  the  equilibrium.  This  stirrer  was  operated  by  a 
small  electric  motor.  It  was  proved  later  that  the  stirrer  was  un- 
necessary and  that  vigorous  shaking  of  the  flask  for  1 minute  was 
sufficient 


7 

Several  tests  were  made  to  prove  the  accuracy  of  this  method 
of  solubility  determination.  It  was  questionable  whether  equilibrium 
could  be  attained  in  such  a short  period  of  agitation  as  has  just  bee> 
described.  Two  180  c.c.  samples  of  distilled  water  were  used  to  test 
the  method.  To  each  enough  n-butyl  alcohol  was  added  to  reach  the 
equilibrium  value  of  16.85  c.c.  fo  the  alcohol  at  25  degrees  C.  by 
the  method  of  shaking  vigorously  for  one  minute.  Then  one  drop  of 
excess  alcohol  was  added.  The  flasks  were  stoppered  with  glass  stop- 
pers and  allowed  to  stand  for  three  days.  During  the  course  of  those 
three  days,  they  were  given  an  occawsiOnal  vigorous  shaking.  At  the 
end  of  that  time  they  were  placed  in  a thermostat  and  left  until  the 
initial  temperature  of  25  degrees  was  attained.  The  excess  drop  of 
alcohol  appeared  at  the  surface  of  the  mixture  as  it  was  initially 
just  after  the  one  minute  shaking.  There  was  no  noticeable  change  in 
its  ifcze.  This  same  procedure  was  used  for  samples  of  N NaCl  soln., 

2h  sodium  sulfate  soln.,and  0.5JM  calcium  chloride  soln.  In  every  case 
complete  saturation  was  proved  to  be  attained  by  the  one  minute  of 
agitation. 

To  test  further  the  method  used  for  the  determinations , two 
180  c.c.  samples  of  normal  sodium  sulfaten  soln.  wereused.  Enough  of 
the  alcohol  was  added  to  reach  the  equilibrium  value  as  indicated  by 
the  method  of  vigorous  shaking  for  1 min.  Asingle  drop  in  excess  was 
added  to  each  fo  the  two  flasks.  They  v/ere  securely  stoppered, and 
placed  on  a shaking  machine.  They  were  allowed  to  shake  for  36  hours* 
removed, and  placed  in  the  thermostat  to  attain  the  original  tenperatu* 
of  25  degrees, C.  That  excess  drop  of  alcohol  had  not  di sappearedin 
either  flask.  There  was  no  noticeable  change  in  its  size  in  either 
case. 

I 


. • 


. 


. 


8 

These  tests  were  accepted  ass  proof  that  the  method  is  satis- 
factory. 

Allof  the  data  embodied  in  this  report  was  obtained  at  con- 
stant temperature  of  25  degrees  C.  It  is  accurate  to  a tenth  of  a c.c 
in  every  case.  All  solutions  were  kept  in  the  thermostat  at  25degrees 

Much  time  was  spent  in  preparing  pure  solutions  of  the  variou 
salts  and  standardizing  them.  Chlorides  were  standardized  by  the  pre- 
cipitation of  AgCl  and  weighing  the  precipitates.  Sulfates  we re  stand- 
ardized by  Barium  Sulfate  precipitation,  Cerous  nitrate  was  standard- 
ized by  precipitating  with  oxalic  acid  and  igniting  the  oxalate  to 
ceric  oxide.  Potassium  ferricyanide  was  standardized  by  precipitating 
the  iron  and  igniting  the  residue  to  ferric  oxide. 

Ill 

data  and  curves 

Plate  I contains  all  of  the  data  of  sections  1,2, 3, 4, 5, 6,  and 
13  of  the  data  sheets.  Plate  II  has  represented  in  its  curves  the 
data  of  sections  1,10, and  11.  Plate  III  has  represented  in  its  curves 
the  data  of  sections  2 and  9.  Plate  IV  contains  data  of  sections  2, 

4, and  7.  Plate  V contains  the  data  of  section  8;Plate  VI  has  thS 
data  of  section  12. 


( Insolubility  of  n-butyl  Alcohol  in  KC1  Solution 

Normalitj'-  c.c.  ofn-butyl  per  180  c.c. 

of  aqueous  soln.of  KC1 . 
0.5— - - 13.80 

1.0  11.65 

1.5  - 9.05 

2.0  — — — - — — 7.87 

3.0  ---  — --  — 5,10 

4. 0 ( Sat.  ) -- 3.40 


(2) Solubility  of  n-butyl  Alcohol  in  Solution. 

Normality  c.c.  of  n-butyl  per  180  c.c. 

of  aqueous  soln.  of  NaCl. 

0.5  — - — - -- 13.0  0 

1.0  10.40 

2.0  ————  — — —— — -7.00 

3.0  — - 4.40 


4.0 


3.25 


5.0 


2.13 


(3Solubility  of  n-butyl  Alcohol  in  LiCl  Solution. 

Normality  c.c.  of  n-butyl  per  180  c.c. 

of  aqueous  soln.  of  NaCl. 

1.0-  — - — 12.30 

2.0 - - 9.10 

2.3---- - 8.00 

( 4)  Solubility  of  n-butyl  Alcohol  in  CaClr,  Solution. 

homality  c.c.  of  n-butyl  per  180  c.c. 

of  aqueous  soln.  of  CaClo. 


0.5 


14.50 


1.0 


12.40 


2.0 


10 


3.0  ---------------  6.40 

4.0  --- 5.12 

6.0-  — — - 2.84 

8.0  1.90 

10.0 -------------------------  1.13 

( 5)  Solubility  of  n-butyl  Alcohol  in  LIgCl0  soln. 

formality  c.c..  of  n-butyl  per  180  c.c. 

of  aqueous  soln.  of  MgClg. 

0. 5------------ ---------------14. 50 

1.0  --------12.90 

1.  5-— — ,-----  — -----11.40 

2.0-  — - - — — ----------- 9. 40 

3.0  

4.0  — .------6.40 

6.0  — 4,17 

8.0—  -------------------3.22 

Sat. ■-- — - — -------------- 1. 30 

( 6)  Solubility  of  n-butyl  Alcohol  in  Ce(N03)3  Solution. 

.Normality  c.c.  of  n-butyl  per  180  c.c. 

of  aqueous  soln.  of  00(1103)3. 

1.0  ----------14.60 

2.0  -- - — -12.75 

3.0  10.40 

4.0  -- --------8.55 

5. 46 6. 68 

( 7 )  Solubility  of  n-butyl  Alcohol  in  a Mixture  of  Equal 


Parts  by  Volume  of  NaCl  and  CaCl2  Solutions. 


formality 


c.c.  of  n-butyl  per  180  c.c. 
of  aqueous  soln.  of  mixture. 


1.0' 


11.50 


2.0- 

3.0- 

4.0- 

5.0- 


8.10 
5.  50 
3.  50 
2.27 


(8) Solubility  of  n-butyl  Alcohol  In  Mixtures  of  CaCl2  and 
NaCl  Solutions  in  Which  the  Cl  Ion  isKept  at  a Constant 
Concentration  of  I NORMAL  but  in  Which  the  Cations  are 
Varied  in  Concentration. 


Normality 


c.c.  of  n-butyl  per  180  c.c. 
of  aqueous  soln.of  mixture. 


1/10  N 

Ca  and  9/10  N Na— - 

— 11.10 

2/10  » 

» " 8/10  " " 

----11 ^10 

3/10  •' 

M " 7/10  " 

--------11.10 

4/10  " 

» » 6/10  " " — «= 

— -11 . 30 

5/10  •' 

»»  M 5/10  " " 

— -11.50 

6/10  " 

" « 4/10  " M 

-------11.55 

7/10  « 

" " 3/10  " 

--------11.75 

8/10  » 

« " 2/10  " »-=- 

--------12.00 

9/10  " 

..  1.  1/10  » «--- 

--------12.20 

0.1  /10  " 

" "9.9/10  " "--- 

0/10  » 

" " 10/10  » "--- 

------  - 10.40 

10/10  " 

" » 0/10  » " — - 

--------12.40 

Solubility 

of  n-butyl  Alcohol 

in  Na2S04  So 

Normality 

0 

• 

0 

. 

0 

3 

1 

of  aqueous  soln.  of  Na2S04. 

0.5 ----- -------- 12.30 

1.0 - 9.00 

1.83 - 5.60 

(10) Solubility  of  n-butyl  Alcohol  in  K2SO4  Solution. 

Normality  c.c.  of  n-butylper  180  c.c. 


of  aqueous  soln.  of  K2SO4 

1.0----------------- — - 9.  50 

1.30----- - — — - — 8.00 

(11) Solubility  of  n-butyl  Alcohol  in  K3Fe(CN)g  Solution. 
.Normality 


12 


c.c.  of  n-butyl  per  180c. c. 
of  aqueous  soln.  of  K.3Fe(  011)5 


1.00- 

2.00- 


2*7.^  , 

• uu' 


•11.20 

-7.65 

■ - 6 . " ■: 


(12) Solubility  of  n-butyl  Alcohol  in  Mixtures  of  NaoS04  and 

NaCI  in  which  the  Na  Ion  is  Kept  at  a Constant  Concentration 
of  I Normal, but  the  SO4  and  Cl  Ionic  Concentrations  are 
Varied. 


Normality 


c.c.  of  n-butyl  per  180c. c. 
of  aqueous  soln. of  Mixture. 


9/10 

N 

Cl  and  1/10 

N 

SO  4- 

• — — — — 10.40 

8/10 

11 

ti  1 

" 2/10 

11 

II 

— — — — 10.30 

7/10 

if 

11  < 

" 3/10 

11 

II 

— — 10.20 

6/10 

n 

11  1 

» 4/10 

n 

II 

— — — — 10.10 

5/10 

n 

11  1 

" 5/10 

11 

II 

• — — 9.80 

4/10 

11 

n 1 

" 6/10 

n 

II 

--------  9.75 

3/10 

n 

11  1 

» 7/10 

11 

II 

__S.60 

2/10 

n 

11 

" 8/10 

11 

II 

---------9.50 

1/10 

it 

ti  1 

» 9/10 

it 

II 

- — — ---9.35 

0.3/10 

n 

n 1 

"9.7/10 

11 

II 

— 9.10 

0/10 

11 

it 

» 10/10 

n 

It 

— — — - 9.00 

10/10 

ti 

n 

» 0/10 

ti 

II 

10.40 

(13) Solubility  of  n-butyl  Alcohol  in  HC1  Solution. 

Normality  c.c.  of  n-butyl  per  180c. c. 

of  aqueous  soln.  of  EC1. 

0.50 15.75 

1.00 - -16.50 


, - 


... 


0 / i 3 Y-  5 & 7 % f “‘i 1 


^ formality  of  aaueous  solutions 


. 


* 


- 


. 


2& 


c . c,  of  alcohol 


16 


Solubility  of  n- butyl  in 
pure  water.; 


PLATE  III 


SOLUBILITY  CURVES  EOR  E-BUTYL  ALCOHOL 
IE  AQUEOUS  SOLUTIONS  OP  SALTS  HAVING 
THE  SAME  CATION  BUT  DIFFERENT  ANIONS. 


3 

A 


f ~ 5"  “T 

NORMALITY 


T 


% 


T~  sc 


al dohol 


PLATE  IV 


SOLUBILITY  CURVES  FOR  U-EUTYL  ALCOHOL 


BALTS 


OF  TWO  PURE 


IN  AQUEOUS  SOLUTIONS 


AND  FOR  A MIXTURE  CONTAINING  EQUAL 


EQUAL 


VOLUMES  OF 


CONCENTRATIONS  AND 


EACH 


n- butyl  in 


pure 


water 


^ NORMALITY 


Normality 


IV 


20 


GENERAL  DISCUSSION  OF  DATA  AND  RESULTS 

The  curves  of  plate  I show  that  the  solubility  of  n-butyl 
alcohol  is  related  in  some  way  to  the  valence  of  the  cation  of  the 
salt  whose  solution  is  used  as  the  solvent.  The  alcohol  is  least  sol- 
uble in  the  aqueous  solutions  of  salts  having  monovalent  cations, and 
most  soluble  in  the  aqueous  solution  of  the  salt  having  a trivalent 
cation.  A possible  explanation  is  that  n-butyl  is  slightly  positive 
in  an  aqueous  solution  of  an  inorganic  salt ; therefore , its  solubility 
is  greater  in  solutions  containing  bivalent  or  trivalent  cations 
than  in  solutions  containing  monovalent  cations.  In  the  case  of  col- 
loids , Schulze  ’ s Law  says: 

"The  coagulatihg  power  of  electrolytes  as  a rule  increases 
rapidly, wi th  the  valence  of  the  active  ion." 

The  active  ion  is  determined  by  the  nature  of  the  sol.  If 
it  is  negative, the  positive  idn  is  the  active  one,aad  vice  versa.  If 
an  excess  of  n-butyl  alcohol  is  added  to  a givrn  quantity  of  any  of 
these  salt  solutions , and  the  mixture  is  shaken  until  saturation  is 
reached, one  can  usually  find  some  of  the  salt  present  in  the  layer 
of  excess  alcohol.  This  indicates  that  if  to  an  aqueous  solution  of 
the  alcohol  some  electrolyte  is  added, part  of  the  alcohol  will  be 
precipitated  and  the  precipitate  will  be  combined  with  some  of  the 
salt.  This  happens  when  an  electrolyte  precipitates  a sol jmorSover , 
the  precipitate  always  has  associated  with  it  some  of  the  electrolyte 
usually  an  electro-equivalent  aifiount  of  the  active  ion. 

Evidence  that  n-butyl  alcohol  forms  a colloid  with  an  aqueous 
solution  of  an  inorganic  salt  and  shows  properties  of  a colloid  is 


furnished  when  some  alcohol  is  shaken  with  a dilute  salt  solution 


• ..  .V.  - 


Anopalescence  appears, and  then  disappears  within  30  minutes  if  the 
mixture  is  allowed  to  stand.  This  opalescence  cannot  be  due  to  cry- 
stals of  aalt  because  its  disappearance  is  not  accompanied  by  precip- 
itation. There  is  a possible  exception  to  this  last  statement.  Pot- 
asaium  sulfate  precipitated  out  when  its  concentrated  solution  was 
saturated  with  the  alcohol.  It  is  likely  that  the  potassium  sulfate 
solution  was  supersaturated.  It  was  a saturated  solution  and  the  low- 
ering of  the  temperature  may  have  supe  rsat urate d it.  Potassium  sulf- 
ate  did  not  precipitate  out  from  dilute  solutions.  The  opalescence 
did  not  occur  in  concentrated  aqueous  solutions  of  salts  tried  be- 
cause the  amount  of  alcohol  in  the  solution  was  insuff i cient ,and  also 
because  the  salt  was  associated  with  most  of  the  water  pres©nt,none 
being  left  to  form  a colloid.  The  salt  soluti ons , however , could  not  bej 
concentrated  enough  at  25  degrees  C.  so  that  n-butyl  alcohol  was  in- 
soluble in  them. 

The  curves  of  Plate  I show  that  the  position  in  the  electro- 
motive series  of  the  elements  , constituting  the  cations  of  the  salts, 
is  in  no  regular  manner  a determining  factor  in  the  solubility  of  the 
alcohol.  Por  instance, Ca  stands  above  Mg  in  the  electromotive  series,; 
but  the  alcohol  is  more  soluble  in  concentrations  of  KgCl0,3  N or 
higher, than  it  is  in  the  same  concentrations  of  GaCl2.  In  concentrat- 
ions less  than  3 N , the  solubility  is  the  same  in  the  two  solutions. 

K stands  above^in  the  electromotive  series  and  the  solubility  of  the 
alcohol  in  KC1  is  greater  at  any  chosen  concentration  than  it  is  in 
ITaCl  of  the  same  concentration.  But, Li  is  lower  in  the  series  than 
either  Ma  orK; nevertheless , tha  solubility  of  the  alcohol  is  greater 

in  LiCl  solution  than  in  either  LaCl  or  KC1  solutions. 

The  solubility  of  the  alcohol  undoubtedly  depends  upon  mol- 


ecular association.  Plate  V shows  that  when  a mixture  of  NaCl  and 


- 

* 

> 

. 

, 

« 

, 


r 


CaCl2  solutions  are  used  for  the  solubility  test, the  addition  of  a 2 
very  small  amount  of  Ca  ion  greatly  increases  the  solubility  of  the 
alcohol.  CaClg  is  outstanding  in  its  power  to  associate  molecules 
with  substances.  N- butyl  alcohol  no  doubt  forms  an  association  pro- 
duct with  CaCl2.  Thus  more  alcohol  can  be  dissolved  in  a solution 
containing  it.  It  is  probable  that  this  association  product  is  at 
least  as  soluble  in  water  as  CaCl2  itself.  Anhydrous  CaCl2  dissolves 

in  n-butyl  alcohol  to  the  extent  of  0.124  gm.per  12  c.c.  This  fact 

association 

indicates  that  molecular/^occurs  with  CaCl2« 

Plate  VI  shows  that  the  presence  of  a very  little  Cl  ion  in 
the  mixturfi  of  NaCl  and  l\Ta2S04  increases  the  solubility  of  the  alcoh^ 
ol  considerably.  The  increase  in  solubility  with  the  increase  in  am- 
ount  of  Cl  ion  present  is  not , however , as  rapid  as  in  the  case  of 
the  Ca  ion  just  described.  Plate  VI  indicates, nevertheless , that  the 
solubility  is  dependent  upon  molecular  association  in  general, and 
is  not  limited  to  the  case  of  CaClo,  It  shows  further  that  anions 
have  an  influence  in  molecular  association  similar  to  that  of  catiois, 
In  order  to  find  out  what  influence  the  H-ion  concentration 
has  upon  the  solubility  of  the  alcohol, the  solubility  of  the  alcohol 
in  aqueo&s  solutions  of  HC1  was  determined.  Plate  I shows  that  when 
the  concentration  of  the  HC1  is  I normal, or  less, the  solubility  of 
the  alcohol  is  less  than  it  is  in  pure  waterjhence  ,e.  small  K-icn 
concentration  does  not  increase  the  solubility  of  the  alcohol.  There- 
fore,we  cannot  attribute  the  increase  of  solubility  that  accompanies 
the  increase  of  valence  o fthe  cations  to  hydrolysis  with  the  conseq  • 
uent  formation  of  H-ions. 

It  has  been  shown (The  Chemistry  of  Colloids  by  W.W. Taylor, 
Chapter  IX)  that  when  a sol  is  precipitated  by  an  electrocute , the 


L2J 


amount  of  the  active  ion  combined  with  the  precipitated  coagulate  is 


proportional  to  the  electro- cbemi cal  equivalent  of  the  ion.  A similar 
relation  may  exist  in  the  phenomena  occuring  in  the  tests  made  in 
this  work.  But, it  is  not  evident  from  the  data  because  other  influenc » 


as  valence  and  association  interfere 


24 


V 

SUMMARY 

(1) The  solubility  of  normal  butyl  alcohol  in  an  aqueous 
solution  of  an  inorganic  salt  depends  upon  the  valence  of  the 
ions  of  which  the  salt  is  composed. 

(2) In  general, the  alcohol  is  most  soluble  in  a given 
concentration  of  the  salt  whose  cation  has  the  highest  valence, 
and  least  soluble  in  the  salt  whose  anion  has  the  highest 
valence. 

(3)  The  valency  rule  for  colloids  that,  in  general  the 
coagulating  powers  of  electrolytes  increase  rapidly  with  the 
valence  of  the  active  ion"applies  to  n-butyl  alcohol  in  aqueous 
solutions  of  electrolytes. 

(4) The  solubility  of  the  alcohol  does  not  depend  upon 
the  electro- chemical  equivalents  of  the  ions  of  the  salt. 

(5) The  greater  solubility  of  n-butyl  alcohol  in  aqueous 
solutions  of  salts  having  cations  of  high  valence  is  not  due 
to  H-ion  concentration. 

(6) The  solubility  of  the  alcohol  depends  upon  the  property 
of  the  salt  to  form  associated  products, and  is  most  soluble  in 

the  aqueous  solution  of  the  salt  that  most  readily  forms  associated 
products. 


, 


. 


25 


BIBLIOGRAPHY 

Frankfurter, J.  A.  C.  S.  ,36,1103(1914) 

Scholes, J.A. C.S, , 33,1309 
Bell , J.Phys . Chem. ,0,537 
Snell , J.Phys. Chem. ,2,458 

Taylor, "TheChemistry  of  Colloids" , Chap. IX. 

Chera.Ahs. ,Vol.l5,Part  I , 1921 , pp . 965 , 1734 , 2374 , 3921 , 
2371,3237. 

Washburn , "Principles  of  Physical  Chemistry',' 
pp. 441-445. 

Brunei,  Crenshaw, and  Tobin, J. A. C. S. , March, 1921 ,pp. 
561-580. 


